medRxiv. 2021 Apr 10:2021.04.07.21255089. doi: 10.1101/2021.04.07.21255089. Preprint.
The US Food and Drug Administration (FDA) authorized treatment of hospitalized COVID-19 patients with Convalescent Plasma (CCP) via the Expanded Access Program (EAP) and the Emergency Use Authorization (EUA), leading to the use of CCP in some 500,000 patients during the first year of the pandemic. We tracked the number of CCP units dispensed to hospitals by blood banking organizations and correlated that usage with hospital admission and mortality data over the course of the year. CCP usage per admission peaked after issuance of the EUA, with more than 40% of inpatients estimated to have received CCP between late September and early November 2020. However, following reports of randomized controlled trials that failed to show clear benefit from CCP, usage/admissions declined steadily to a nadir of less than 10% in March 2021. We found a strong inverse correlation (Pearson's correlation coefficient of -0.5176 with P = 0.00242) between CCP usage/hospital admission and deaths occurring two weeks after admission, and this finding was robust to examination of deaths taking place one, two or three weeks after admission. Changes in the number of hospital admissions, prevalence of variants, and age of patients could not explain these findings. We estimate that the retreat from CCP usage, a phenomenon we termed 'plasma hesitancy', might have resulted in 29,000 to 36,000 excess deaths in the period from mid-November 2020 to February 2021. These results highlight the need for additional studies to ascertain the variables associated with efficacy and/or provide other explanations for the robust relationships observed in this study.